Easy Python CSV Tutorial
Sometimes we want persistently store data from our Python programs that can’t be represented in a simple 1 dimensional list.
This data has 2 dimensions, and in reality we are storing table data.
This data needs to stored to and read from a CSV file.
This table above can be stored in a Comma Separated Values file, that might look a bit like this:
To read from and write to these files, it’s easiest to use the csv module!
Reading from CSV Files
Reading from a csv file is easy….
Let’s suppose we haver a csv file that looks like this:
All we need it to write a program that:
- Opens a file connection
- Starts the CSV reader engine
- Loads all of the stored file data into a Python 2D list
The result is that your program now contains a list called scores that contains the values loaded in. Here is what it looks like in Python:
scorelist = [[‘bob’, ‘jones’, ’20’], [‘fred’, ‘wilson’, ’30’], [‘sarah’, ‘smith’, ‘100’], [‘harry’, ‘harrington’, ‘5000’]]
Writing to CSV Files
Saving data to a CSV file is just as easy, you just need to :
- open the file in append mode(or write mode of you want to replace the contents of the file!)
- start the writer engine.
- write the line you want to write
- close the file to save it.